A novel technique has been devised by Lim and associates to microencapsulate various cells and organelles by making use of an alginate solution. Such encapsulation can be performed so that capsule size can be varied to accomodate several cells to several thousand cells. The size of pores in these capsules can be regulated so that only small molecules and small proteins can enter or leave these spheres. Dr. Lim and his associates have imparted this technology to us for the purpose of devising techniques of transplantation of endocrine cells in order to overcome hormone deficient states in a physiological manner. Thus, we will use encapsulated pancreatic islets (without the need of immunemodulation because the capsule membrane is permeable to glucose and insulin but totally impermeable to the host's cellular and humoral immune system) to treat induced diabetes in rats; thus parathyroid cells will be encapsulated to treat hypoparathyroidism in parathyroidectomized rats; and thus adrenal cell lines will be used to treat surgically induced Addison's disease by using the encapsulation technique. The goals of this novel, pilot study are to learn more about the in vivo regulation of hormone secretion and to provide practical data as to the feasibility of using this technique in man. This use would be especially important in the brittle diabetic where even implantable insulin delivery systems do not readily afford true physiological regulation of insulin secretion and this methodology would allow this to occur without using immunosuppressive therapy which would worsen the diabetic state. Likewise physiological replacement of parathyroid hormone in man might be similarly realized. The study calls for a system investigation of the optimal location of implantation, the number of capsules needed, and the duration of the physiological release of the active hormones from such capsules to correct the hormone deficiencies from the above mentioned disease states. Emphasis will be given to pancreatic islets because the technology for their isolation and encapsulation has already been determined in our laboratory.